This invention relates to machine tools. In particular, the invention relates to a machine tool which is portable so that it can be easily transported to the work piece on which operations are to be performed, which can perform a range of operations on the work piece and which can perform these operations at locations remote from the drive of the machine tool.
In many industrial installations and power stations the work piece may form a part of a larger piece of equipment and cannot be removed so that any machining or other operations have to be performed on site. It is not uncommon that the parts of the work piece upon which operations are to be performed are relatively inaccessible. Further, the operations required on the work piece may comprise not only the removal of material by a suitable cutting tool or tools, but also the application of material to a surface in order to restore the surface to a previous size, the built up material then requiring to be formed to the desired size and surface finish.
The present invention therefore seeks to provide a machine tool which is sufficiently portable so that it can be set up on site, which can accommodate a variety of tools and which can operate on surfaces of a work piece remote from the access to that work surface.
Accordingly, the present invention provides a machine tool, the machine tool comprising tool support means, a rotatably driveable carriage to which the tool support means is secured, and a base on which the carriage is supported for rotation, the base being securable to a work piece upon which operations are to be performed, the tool support means being capable of receiving at least two tools for performing operations on the work piece, means being provided to offset the axis of rotation of at least one of said tools from the axis of the surface upon which operations are to be performed.
The tool support means may comprise at least two spaced apart bearing surfaces.
In one arrangement, three bearing surfaces may be provided, one surface being on the carriage, and two surfaces being on a hollow shaft forming part of an intermediate support structure to which the base is secured and which itself is secured to the work piece.
The tool may include a cutting tool mounted on a driveable spindle, the spindle being eccentrically mounted on a shaft which is located in the tool support means.
The shaft can be securable to the rotatable carriage and the shaft can be attached to a drive housing having height adjustment means to position the shaft vertically with respect to the carriage and the tool support means.
The height adjustment means can comprise a spindle rotatably mounted on the carriage engaging a threaded portion of the drive housing.
The cutting tool can comprise a milling cutter.
The other one of said at least two tools can comprise a welding head arranged to deposit material upon a surface already prepared by the milling cutter.
The machine tool can include a cutter head having at least one adjustable tool, the adjustment of which can be remotely controlled.
A further feature of the present invention is the provision of means for adjusting the eccentricity of the cutter head drive shaft, so that the machine tool can mill a variety of diameters of the work piece.
Further features of the present invention can include the provision of double reverse helical gears on the drive shaft, a twin drive for the rotatable table of the machine tool, and twin bearings for the tool support means.